Conventionally, discarded plastics discarded from households or the like are disposed of by incineration or in landfills. However, incineration and landfills have come to cause social problems such as impact on the global environment and shortages of landfill sites. Accordingly, in recent years, there has been an effort to sort/collect or recycle discarded plastics. In order to recycle the discarded plastics, it is necessary to identify the kinds of discarded plastics.
Conventional methods for identifying the kinds of discarded plastics include, for example, a method utilizing specific gravities. However, the method utilizing specific gravities has had a problem in that plastics are difficult to identify when there is little difference in their specific gravities.
Also, another method for identifying the kinds of discarded plastics is a method utilizing infrared light, for example. As an example of this method utilizing infrared light, the method capable of identifying, for example, plastics whose surface is coated, plastics to which dirt or the like adheres and plastics containing flame retardants in a highly precise manner has been suggested (see JP 2003-202291 A, for example). In this method, a test piece is cut out by punching out a discarded plastic partially, and infrared light is made to enter one face of this test piece (a face corresponding to a surface of the discarded plastic) and the other face, which is different from the above-noted one face (a section taken at the time of forming the test piece (a face exposed for the first time when cut out as the test piece)), while varying a wave number for each face, thereby detecting the intensity (or absorbance) of totally-reflected infrared light corresponding to each wave number. More specifically, as shown in FIG. 15A, for example, a test piece 101 first is held with a chuck 104, and one face of the test piece 101 is brought into close contact with a detection hole (an identifying and detecting portion) 103 for an identifying stage 102 provided in a plastic identifying apparatus. Infrared light is made to enter the one face of the test piece 101 via the identifying and detecting portion 103 so as to identify the one face of the test piece 101. The chuck 104 is provided so as to be rotatable by a rotating portion 105 around an axis of rotation in the horizontal direction (a direction of a plane perpendicular to a B axis direction shown in FIG. 15A) while holding the test piece 101. As shown in FIG. 15B, by rotating the chuck 104 by 90° in a direction indicated by C, another face of the test piece 101 is brought into close contact with the identifying and detecting portion 103, thus identifying this another face. With this method, it becomes possible to identify the surface state of discarded plastics (the kinds of dirt and coating, the degree of degradation and dirt), the kinds of discarded plastics and the kinds of flame retardants that are contained.
However, in the methods and apparatuses of identifying discarded plastics in a highly precise manner by detecting two different faces of a test piece as described above, it has been necessary to hold the test piece with the chuck and rotate the chuck so as to change the test piece face to be analyzed. Thus, in these methods, it has taken time to hold the test piece with the chuck or release it and to rotate the test piece by 90°. Moreover, a large number of processes have been required for identification.
Further, in order to hold the test piece with the chuck, the shape of the test piece is restricted in many ways: for example, the test piece has to be thick enough to be held and has to have a shape adapted for the chuck shape. Moreover, at the time of holding the test piece with the chuck, there has been a risk of dropping the test piece due to chucking error, posing a problem in workability.